So far ultraviolet lamps have been used to sterilize or disinfect various kinds of things. The ultraviolet lamp for use with a small capacity tank has a lifetime as long as 2000 to 3000 hours under the continuous driving condition or it has a lifetime one half of the above-mentioned lifetime under the intermittent driving condition. Further, due to the sizes of a glow tube and a stabilizer for actuating itself, the ultraviolet lamp becomes large in size in view of a small capacity tank. Thus, it is difficult to make the ultraviolet lamp compact in size. Also, in an automatic vending machine for vending drinks, for example, such means is not yet used that keeps a supplying pipe for supplying various kinds of drinks clean.
All of tanks of small capacity used as a water purifier and an automatic drink vending machine, water tanks used as a purified water container, a humidifier, a dehumidifier and an air cleaner, a water container for holding a contact lens and various kinds of small water supplying tanks must be kept clean and in good sanitary condition. If the ultraviolet lamp is utilized to sterilize the inside of such small tank, since it is difficult to minimize the lamp due to the above-mentioned reason, the ultraviolet lamp radiates even the unnecessary portion of the tank, which fact is uneconomical. Also, it is very difficult to mount such ultraviolet lamp on the tank.
Preferably, the inside of containers for tooth brushes, combs and so on should be maintained in a clean, -sanitary condition and also, articles to be kept in the container must be kept clean. If the ultraviolet lamp is used to sterilize such container of relatively small size, the lamp cannot be made compact in size due to the above mentioned reasons so that the lamp irradiates the unnecessary portion of the tank which fact is uneconomical and that the lamp cannot be mounted to the container itself.
Also, it is desirable that a pipe-shaped portion (hereinafter generally referred to as a nozzle) through which sterilized water and drinking water are supplied be maintained in a sanitary, clean condition. If the ultraviolet lamp is used to sterilize such small, restricted portion, the ultraviolet lamp cannot be made compact in size due to the above-mentioned reason so that it irradiates the unnecessary portion, which fact is uneconomical and that it cannot be mounted to the nozzle without difficulty.
Further, if the ultraviolet lamp is used to sterilize the drink supplying pipe of the automatic drink vending machine or the like, the ultraviolet lamp cannot be made compact in size due to the above-mentioned reasons so that it occupies a large space, and also there may be a fear that the lamp is broken and that a harmful insect enters the vending machine.